<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <!--<form action="https://localhost:8080/pay/add" method="post">
        <input type="text" name="userId">
        <input type="text" name="count">
        <input type="text" name="money">
        <input type="submit">
    </form>-->
    <input accept="image/*" name="upimage" id="upload_file" type="file">
    <textarea id="base64_output" name="Word" style=" width:820px"></textarea>

    <script type="text/javascript">
        document.getElementById("upload_file").onchange = function () {
            gen_base64();
        };
        function $_(id) {
            return document.getElementById(id);
        }
        function gen_base64() {
            var file = $_('upload_file').files[0];
            r = new FileReader();  //本地预览
            r.onload = function(){
                $_('base64_output').value = r.result;
            }
            r.readAsDataURL(file);    //Base64
        }
    </script>

</body>
</html>